1. Field of the Invention:
The present invention relates generally to a parts feeder of the type wherein parts held in a rotating drum provided in place of a conventional bowl are fed in order along a linear passage at high speed and with reliability for conveyance to the next processing operation, and more particularly to a parts feeder which is suitable for use with various parts having irregular cross sections and requiring orientation in conveyance.
2. Description of the Prior Art:
In the production of a slide fastener or the like article composed of a plurality of parts of different configurations, the parts are supplied to an assembling station in the order prescribed by an assembling schedule, and each of the parts thus supplied is then assembled onto a predetermined position while keeping the same posture. In connection with this assembling operation, a parts feeder as disclosed in Japanese Patent Laid-open Publication No. HEI 5-178447 is generally used for conveyance of small parts. The disclosed parts feeder is of the bowl type including a bottomed vibrating bowl with a spiral parts feed passage on an inside wall surface thereof, and a plate-like chute interconnecting an outlet of the parts feed passage in the bowl and a parts supplying portion of the next processing station.
As an another example, U.S. Pat. No. 2,052,179 discloses a parts feeder for feeding fastener elements for a slide fastener. The disclosed parts feeder includes a horizontal drum driven to rotate in one direction about a substantially horizontal axis, a downwardly inclined tubular chute extending from the inside of the horizontal drum to the outside of the same along the axis of the horizontal drum. An inner cylindrical wall surface of the horizontal drum is provided with a plurality of wing plates circumferentially spaced at predetermined intervals and projecting radially inwardly at predetermined angles toward the axis of the horizontal drum. Upon rotation of the horizontal drum, the parts held in batches in the horizontal drum are scooped or taken up by the wing plates and when the wing plates reach an upper oblique position of the drum, the parts slide down from the wing plates onto a tray and then received in a longitudinal slit formed in an upper surface of the tubular chute.
Thereafter, the parts slides down along the slit of the tubular chute for conveyance to a delivery chute connected to the next processing station. In this instance, if parts while being fed down the tubular chute has an undesired posture or orientation, the parts will to move into the internal space of the tubular chute and then fall down to the outside of the tubular chute through a discharge hole formed in a portion of a bottom surface of the tubular chute.
The bowl type parts feeder shown in Japanese Patent Laid-open Publication No. HEI 5-178447 has a drawback in that since conveyance of the parts relies on vibration of the bowl in the circumferential direction thereof, not only the parts are unlikely to move or advance smoothly along the spiral feed passage, but also it is difficult to advance the parts on the feed passage smoothly. The bowl type part feeder, therefore, has a limitation or difficulty in increasing the parts conveyance speed. Furthermore, it is doubtful that the parts can be reliably transferred from the spiral feed passage to the plate-like chute.
The drum-type parts feeder disclosed in U.S. Pat. No. 2,052,179 has no means for positively advancing the parts. Instead, the parts simply slide down the chute by their own weights while they are guided in the slit of the tubular chute. Accordingly, smooth conveyance of the parts is difficult to achieve, and the parts conveyance speed cannot be increased. Further, depending on the shape of parts to be conveyed, the number of parts which can be received in the slit may be limited, thus lowering the productivity. The disclosed drum type parts feeder cannot make a discrimination between the front and the reverse of the respective parts to be fed, so that it can not recognize and remove parts in reverse or wrong postures. Accordingly, the parts feeder is not suitable for use with parts, such as fastener elements for a slide fastener, which require orientation in conveyance.